Add DesktopFrameCGImage

No functional change. This makes the code more generic
and this reduces the size of screen_capturer_mac.mm

Bug: webrtc:8652
Change-Id: I37743ba385fea5e1b40df3b094bfc321b8d796ae
Reviewed-on: https://webrtc-review.googlesource.com/65082
Commit-Queue: Julien Isorce <julien.isorce@chromium.org>
Commit-Queue: Zijie He <zijiehe@chromium.org>
Reviewed-by: Zijie He <zijiehe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#22684}

modules/desktop_capture/BUILD.gn

@@ -175,6 +175,8 @@ if (is_mac) {
     visibility = [ ":desktop_capture" ]
     sources = [
       "mac/desktop_configuration.mm",
+      "mac/desktop_frame_cgimage.h",
+      "mac/desktop_frame_cgimage.mm",
       "mac/screen_capturer_mac.h",
       "mac/screen_capturer_mac.mm",
       "mouse_cursor_monitor_mac.mm",

modules/desktop_capture/DEPS

@@ -4,6 +4,9 @@ include_rules = [
 ]
 
 specific_include_rules = {
+  "desktop_frame_cgimage\.h": [
+    "+sdk/objc",
+  ],
   "screen_capturer_mac\.mm": [
     "+sdk/objc",
   ],

modules/desktop_capture/mac/desktop_frame_cgimage.h

@@ -0,0 +1,48 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_DESKTOP_CAPTURE_MAC_DESKTOP_FRAME_CGIMAGE_H_
+#define MODULES_DESKTOP_CAPTURE_MAC_DESKTOP_FRAME_CGIMAGE_H_
+
+#include <CoreGraphics/CoreGraphics.h>
+
+#include <memory>
+
+#include "modules/desktop_capture/desktop_frame.h"
+#include "sdk/objc/Framework/Classes/Common/scoped_cftyperef.h"
+
+namespace webrtc {
+
+class DesktopFrameCGImage final : public DesktopFrame {
+ public:
+  // Create an image containing a snapshot of the display at the time this is
+  // being called.
+  static std::unique_ptr<DesktopFrameCGImage> CreateForDisplay(
+      CGDirectDisplayID display_id);
+
+  ~DesktopFrameCGImage() override;
+
+ private:
+  // This constructor expects |cg_image| to hold a non-null CGImageRef.
+  DesktopFrameCGImage(DesktopSize size,
+                      int stride,
+                      uint8_t* data,
+                      rtc::ScopedCFTypeRef<CGImageRef> cg_image,
+                      rtc::ScopedCFTypeRef<CFDataRef> cg_data);
+
+  const rtc::ScopedCFTypeRef<CGImageRef> cg_image_;
+  const rtc::ScopedCFTypeRef<CFDataRef> cg_data_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(DesktopFrameCGImage);
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_DESKTOP_CAPTURE_MAC_DESKTOP_FRAME_CGIMAGE_H_

modules/desktop_capture/mac/desktop_frame_cgimage.mm

@@ -0,0 +1,67 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "modules/desktop_capture/mac/desktop_frame_cgimage.h"
+
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+// static
+std::unique_ptr<DesktopFrameCGImage> DesktopFrameCGImage::CreateForDisplay(
+    CGDirectDisplayID display_id) {
+  // Create an image containing a snapshot of the display.
+  rtc::ScopedCFTypeRef<CGImageRef> cg_image(CGDisplayCreateImage(display_id));
+  if (!cg_image) {
+    return nullptr;
+  }
+
+  // Verify that the image has 32-bit depth.
+  int bits_per_pixel = CGImageGetBitsPerPixel(cg_image.get());
+  if (bits_per_pixel / 8 != DesktopFrame::kBytesPerPixel) {
+    RTC_LOG(LS_ERROR) << "CGDisplayCreateImage() returned imaged with " << bits_per_pixel
+                      << " bits per pixel. Only 32-bit depth is supported.";
+    return nullptr;
+  }
+
+  // Request access to the raw pixel data via the image's DataProvider.
+  CGDataProviderRef cg_provider = CGImageGetDataProvider(cg_image.get());
+  RTC_DCHECK(cg_provider);
+
+  // CGDataProviderCopyData returns a new data object containing a copy of the provider’s
+  // data.
+  rtc::ScopedCFTypeRef<CFDataRef> cg_data(CGDataProviderCopyData(cg_provider));
+  RTC_DCHECK(cg_data);
+
+  // CFDataGetBytePtr returns a read-only pointer to the bytes of a CFData object.
+  uint8_t* data = const_cast<uint8_t*>(CFDataGetBytePtr(cg_data.get()));
+  RTC_DCHECK(data);
+
+  DesktopSize size(CGImageGetWidth(cg_image.get()), CGImageGetHeight(cg_image.get()));
+  int stride = CGImageGetBytesPerRow(cg_image.get());
+
+  return std::unique_ptr<DesktopFrameCGImage>(
+      new DesktopFrameCGImage(size, stride, data, cg_image, cg_data));
+}
+
+DesktopFrameCGImage::DesktopFrameCGImage(DesktopSize size,
+                                         int stride,
+                                         uint8_t* data,
+                                         rtc::ScopedCFTypeRef<CGImageRef> cg_image,
+                                         rtc::ScopedCFTypeRef<CFDataRef> cg_data)
+    : DesktopFrame(size, stride, data, nullptr), cg_image_(cg_image), cg_data_(cg_data) {
+  RTC_DCHECK(cg_image_);
+  RTC_DCHECK(cg_data_);
+}
+
+DesktopFrameCGImage::~DesktopFrameCGImage() = default;
+
+}  // namespace webrtc

modules/desktop_capture/mac/screen_capturer_mac.mm

@@ -12,6 +12,7 @@
 
 #include "modules/desktop_capture/mac/screen_capturer_mac.h"
 
+#include "modules/desktop_capture/mac/desktop_frame_cgimage.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/constructormagic.h"
 #include "rtc_base/logging.h"
@@ -405,32 +406,19 @@ bool ScreenCapturerMac::CgBlit(const DesktopFrame& frame, const DesktopRegion& r
       }
     }
 
-    // Create an image containing a snapshot of the display.
-    rtc::ScopedCFTypeRef<CGImageRef> image(CGDisplayCreateImage(display_config.id));
-    if (!image) {
+    std::unique_ptr<DesktopFrameCGImage> frame_source =
+        DesktopFrameCGImage::CreateForDisplay(display_config.id);
+    if (!frame_source) {
       continue;
     }
 
-    // Verify that the image has 32-bit depth.
-    int bits_per_pixel = CGImageGetBitsPerPixel(image.get());
-    if (bits_per_pixel / 8 != DesktopFrame::kBytesPerPixel) {
-      RTC_LOG(LS_ERROR) << "CGDisplayCreateImage() returned imaged with " << bits_per_pixel
-                        << " bits per pixel. Only 32-bit depth is supported.";
-      return false;
-    }
+    const uint8_t* display_base_address = frame_source->data();
+    int src_bytes_per_row = frame_source->stride();
+    RTC_DCHECK(display_base_address);
 
-    // Request access to the raw pixel data via the image's DataProvider.
-    CGDataProviderRef provider = CGImageGetDataProvider(image.get());
-    rtc::ScopedCFTypeRef<CFDataRef> data(CGDataProviderCopyData(provider));
-    RTC_DCHECK(data);
-
-    const uint8_t* display_base_address = CFDataGetBytePtr(data.get());
-    int src_bytes_per_row = CGImageGetBytesPerRow(image.get());
-
-    // |image| size may be different from display_bounds in case the screen was
+    // |frame_source| size may be different from display_bounds in case the screen was
     // resized recently.
-    copy_region.IntersectWith(
-        DesktopRect::MakeWH(CGImageGetWidth(image.get()), CGImageGetHeight(image.get())));
+    copy_region.IntersectWith(frame_source->rect());
 
     // Copy the dirty region from the display buffer into our desktop buffer.
     uint8_t* out_ptr = frame.GetFrameDataAtPos(display_bounds.top_left());